I probably have to take some contrary views here ...
DCDriver
Vmcg is related to thrust output. As a result, other things remaining constant, the 'real' Vmcg will reduce for typical turbine powered aircraft as the pressure height and OAT increase. Scheduled min V1 relates to the standard published Vmcg determined for specified certification conditions. Looking at the 732 with -17 motors, for instance, the real world Vmcg varies from 105 kt at sea level down to 87 kt at 10,000 feet and 30C (ref QRH). The minimum scheduled V1, based on the certification data, remains constant. The handling considerations, however, vary considerably with the variation in real world Vmcg.
VR principally relates to V2 and is scheduled to provide V2 (or thereabouts) following a V1 failure as the aircraft completes the takeoff rotation flare at 35 feet.
V2min (as opposed to overspeed or improved performance V2) relates to both Vs and Vmca - the Vs limitation applying for higher weight and the Vmca limitation applying at the low end of the weight range. For normal takeoff heights, Vs is sensibly dependent only on weight while real world Vmca, in a manner similar to Vmcg, will reduce with decreasing thrust output. Scheduled data, however, will be predicated on certification data.
Saltydog,
The (I presume simplified) performance documents you have referred to have to be looked at in the context of their construction. The AFM will provide for a range of acceptable speed schedules. If a simplified set of schedules is prepared then the schedules will vary on the basis of how the basic takeoff chart used has been prepared. Although such an answer is not very helpful in the context of your question, one has to look at the specific documents to which you refer in order to offer a sensible engineering answer.
av8er,
I would urge considerable caution when operating in the vicinity of minV1. It is worth keeping in mind that Vmcg is not a cut and dried concept. The value published is for specific conditions and, if the conditions vary adversely, then the real world Vmcg can increase - putting an apparently legitimate takeoff at increased risk of control loss in the event of an engine failure. This consideration is mainly a concern in the situation where the aircraft takes off on a minV1 schedule with a high crosswind. Typically, the real world Vmcg will increase above the published figure (for US aircraft - based on nil wind) by around half of the crosswind component.
[ 14 October 2001: Message edited by: john_tullamarine ]